In his 40-minute address, Calderon sharply criticized Arizona's tough new immigration law and the United States' refusal to ban assault weapons, which are being used in the violent drug-gang shootouts in Mexico.

Afterward, Sen. John Cornyn, R-Texas, said Calderon "crossed a line" by urging changes in gun policy, and Sen. John McCain, R-Ariz., who's become a hard-liner on curbing illegal immigration, declared, "I've never heard of another country's president coming here and criticizing the United States like that."

Democrats were more supportive.

"I don't know what the protocol is, but I don't think he crossed any line," said Rep. Ed Pastor, D-Ariz.

A Democratic plan, unveiled April 29, would create a path to citizenship for most of the estimated 11 million people who are in this country illegally now and would provide stronger security along the U.S.-Mexican border. The security features are aimed at wooing Republicans, who've said that security is their top priority.

However, with congressional elections less than six months away, there's been no movement toward compromise, and the bill is expected to get little traction in the current Congress.

Instead, it's become one of the most divisive, most partisan issues lawmakers confront, and Calderon's visit to Washington, which included talks Wednesday with President Barack Obama, has done little, if anything, to close the gap.

"There's such a wide divide, I'm not sure anything in his visit did anything to close the divide," said Sen. Claire McCaskill, D-Mo.

"It doesn't help," added Sen. Orrin Hatch, R-Utah.

The schism was apparent Thursday, as so few Republicans showed up for Calderon's address that four of the seven and a half Republican rows in front of Calderon, about 40 seats, were filled largely by student pages.

Calderon offered blistering comments about the Arizona law, which is slated to go into effect July 29. It would permit law enforcement officers to check the immigration status of people they stop for other reasons. Obama has said the Justice Department will review the law.

"I strongly disagree with the recently adopted law in Arizona," the Mexican president said, as most Democrats stood and cheered. He denounced it as "a terrible idea using racial profiling as a basis for law enforcement."

Republicans reacted strongly.

"It's inappropriate for a head of state to question our laws, especially when the state of Arizona only acted in the best interest of its citizens and with the support of 70 percent of its people," said Hatch, a senior Senate Judiciary Committee member.

Sen. Jeff Sessions of Alabama, the top Judiciary Republican, said Calderon was simply wrong.

"They cannot use racial profiling in Arizona," he said. "The important thing is that we stop lawlessness at the border."

Calderon also stirred Republican ire with comments about assault weapons. Tough 1994 U.S. restrictions on 19 such weapons expired nearly six years ago, and Calderon urged that they be reinstated. He maintained that there are more than 7,000 shops along the border where such weapons can be obtained.

"Today, these weapons are aimed by the criminals not only at rival gangs but also at Mexican civilians and authorities," he said. "And with all due respect, if you do not regulate the sale of these weapons in the right way, nothing guarantees that criminals here in the United States, with access to the same powerful weapons, will not decide to challenge American authority and civilians."

Republicans weren't pleased with those remarks, either.

"I have great respect for President Calderon, but he really shouldn't turn this into an opportunity to tell us we should change our laws," Cornyn said. He said that the Second Amendment, which gives Americans the right to bear arms, wasn't a subject for diplomatic discussions.